Railcar moving vehicles having a weight transfer capability have been sold the railroad industry for years, being of a design which is typified for example by White U.S. Pat. Nos. 4,497,257; 4,537,137; and 4,380,198; and Lich et al. U.S. Pat. No. 4,878,436, among others.
These railcar moving vehicles typically are too light to effectively pull a loaded railcar without significant wheel slippage. Therefore, a weight transfer mechanism is provided, in which the coupler of the railcar moving vehicle, which connects to the railcar, may be driven upwardly, typically by hydraulic cylinders. This upward force is of course transferred to the coupled railcar, which has the effect of "transferring" weight from the railcar to the railcar moving vehicle. Thus, the wheels of the railcar moving vehicle are provided with more traction, which permits the vehicle to effectively move heavily loaded railcars.
If the railcar is fully loaded, the operator of the moving vehicle can hook up to the car and typically position the coupler lift mechanism to the full-on position, thus transferring weight of typically up to 48,000 pounds onto the railcar moving vehicle. However, if the railcar is partially full or empty, then the operator must make a judgment of how much weight he can transfer to his vehicle. If his judgment is conservative, then he does not transfer the maximum possible amount of weight, which reduces the maximum tractive effort available for the vehicle. However, if the operator overestimates the amount of weight transfer, a more serious result can take place, in that the railcar can be lifted off of one of its railcar truck wheels. The railcar can be actually separated from one of its truck wheels so that, when the railcar moving vehicle moves the railcar, the truck wheel does not move with it. Potentially serious damage can take place in this instance.
In accordance with this invention, a simple apparatus and technique is provided for determining the point at which a maximum amount of load has been transferred from the railcar to the car moving vehicle, but the railcar has not yet been lifted off of its truck, so that the railcar can be effectively moved by the moving vehicle of this invention, even with an operator who is relatively unskilled. This substantially eliminates the accidental separation of the railcar from one of its truck wheels.